Wouldn't a nil ECDSA key be a security risk?

If a private key is available, the public key can be derived from the private key using scalar multiplication. This is how ecdsa.GenerateKey works by itself - it first generates a private key from the provided random byte stream and then derives a public key from that private key.

I don't see how this can be a security risk, but allowing a public key that has a curve but a nil value is definitely a messy API.